1. Field of the Invention
The present invention relates to a vibration wave driving apparatus. Particularly, the present invention relates to a vibration wave driving apparatus for relatively moving an ultrasonic vibrator and a driven body by combining vibrations of different vibration modes.
2. Description of the Related Art
A vibration wave driving apparatus for relatively moving an ultrasonic vibrator and a driven body by combining vibrations of different vibration modes has been proposed.
Such a vibration wave driving apparatus has a pressure-application structure to generate a frictional force between the ultrasonic vibrator and the driven body.
Further, the vibration wave driving apparatus is given a support structure for maintaining abutment of frictional surfaces formed between the ultrasonic vibrator and the driven body with an appropriate relation.
As this support structure, some methods have been proposed.
One of them is a configuration in which an ultrasonic vibrator or a driven body is held by a biasing component formed in a planar spring shape (see Japanese Patent Application Laid-Open No. 2006-301457). In this case, the biasing component (member) serves as a supporting member. Another one of them is a configuration in which an ultrasonic vibrator or a driven body is rotatably held by a mechanism through a sphere-shaped member (see Japanese Patent Application Laid-Open No. 2006-301454).
The following describes a necessary requirement for the supporting member having such a support structure.
FIG. 10A shows a state where an ultrasonic vibrator 3 and a driven body 4 abut with each other in parallel (in a state where their respective frictional surfaces come into contact with each other).
In this figure, an X-axis indicates an occurrence direction of relative motion of a vibration wave driving apparatus. Further, a Z-axis indicates a normal-line direction with respect to frictional surfaces of the ultrasonic vibrator 3 and the driven body 4, and a Y-axis indicates a direction orthogonal to the X-axis and the Z-axis.
When each of the ultrasonic vibrator 3 and the driven body 4 is provided ideally, abutting surfaces of the ultrasonic vibrator 3 and the driven body 4 are disposed parallel to each other.
By giving an applied pressure (not shown) in the Z-direction in such a positional relationship to displace the ultrasonic vibrator 3 or the driven body 4 in the Z-direction, an abutment force can be given between the frictional surfaces thereof.
However, in a practical sense, it is extremely difficult to provide the frictional surfaces of the ultrasonic vibrator 3 and the driven body 4 at parallel positions due to manufacturing errors of components, installation errors, and the like.
Therefore, some ideas are necessary for the holding of the ultrasonic vibrator 3 or the driven body 4.
The support structure has a degree of freedom to a rotational displacement θx (a direction of an arrow dθx in FIG. 10C) around the X-axis and a rotation displacement θy (a direction of an arrow dθy in FIG. 10D) around the Y-axis. Further, the support structure is provided such that the ultrasonic vibrator or the driven body is held to be able to move in the Z-axis direction (a direction of an arrow dz in FIG. 10B), thereby maintaining imparting of the abutment force and a surface-contacting state of their respective frictional surfaces.